Apparatus for secondary recovery in oil wells



Jan. 6, 1953 I J. NIXON 2,624,410

APPARATUS FOR SECONDARY RECOVERY IN-OIL WELLS Filed July 25. 1947 2 SHEETSSHEET l Jeddy D. Nixon awe/MM J. D. NIXON APPARATUS FOR SECONDARY RECOVERY IN OIL WELLS Jan. 6, 1953 2 SHEETSSHEET 2 Filed July 25, 1947 Jeaay Nixon v Qrwem M Patented Jan. 6, I953 UNITED STATES PATENT OFFICE APPARATUS FOR SECONDARY RECOVERY IN OIL WELLS J eddy D. Nixon, New Braunfels, Tex.

Application July 25, 1947, Serial No. 763,648

7 Claims.

This invention relates to new and useful improvements in apparatuses for secondary recovery in oil wells.

There are a certain class of oil wells known as"stripperror low production wells. These wells are pumping wells andare usually rela tively shallow and commonly less than a thousand feet deep, although many of these wells are deeper. Such wells under ordinary pumping conditions produce various quantities frequently under ten barrels a day and often, less than five barrels per day. Because of'their low production, they must be economically operated and the maintenance costs must be low, otherwise they would not be profitable. These wells are usually umped with a jack and motive power is available at many wells. J

When the production of a, Well declines to 2to 4 barrels of oil per day, it is not generally con sidered profitable to pump them. Thereare a number of oilfields and oilwells which have been abandoned because they could not be pro' duced on a paying basis, although it is known that large quantities of residual oil remainin these formations.

It has been found that by pulling a vacuum on the producing formation, the oil production, per day, is increased. So far as I know the vacuum methods heretofore employed include a central plant equipped with expensive vacuum pumps and connected to a plurality of wells. Vacuum pumps create a vacuum by piston displacement, which produces a pulsating orvibratory suction on the formationand thus, the vacuum is not steady or stable. Such systems often cause caving of the formation, clogging'or other troubles. These plants are expensive to purchase nd install, operate and maintain and when the plant is shut down, production from all of the wells is stopped. Because of the distance from the wells, the plant being centrally located, the suction lines are long, are subject to leaks and the time required to build up a vacuum in a well frequently runs 24 hours. This leads to relatively high costs.

One object of the invention is to provide an improved system, whereby the production of oil from wells of the class described, which have declined in production, may be profitably increased, or which, may be utilized to rehabilitate depleted or abandoned wells or with wells redrilled in depleted or abandoned oil fields,

Another object of the invention isto provide an improved systemof secondary recovery, whereby an individual welljmay be profitably produced in a simple, efficient and economical manner with an individual unit which may be purchased, installed, operated and maintained at a low cost.

A further object of the invention is to provide an improved system wherein the vacuum is created and maintained in the well by circulating a, liquid stream, preferably water, under a relatively high velocity through means for setting up a suction at a point in the stream and utilizing the suction to pull the vacuum' in the well, whereby gas or air in the well is sucked into the liquid stream, and then, reducing the velocity of the stream and separating the gas or air therefrom. The method is made more economical by recirculating the liquid stream.

A still further object of the invention is to provide an improved means of pulling a vacuum in a an oil well, whereby a steady and stabilized suction'is exerted on the formation which prevents caving, clogging and other troubles and assures more efiicient production.

Another object of the invention is to provide an improved system of the character described wherein the vacuum pulled on an individual well may be controlled and regulated.

Still another object of the invention is to pro videan improved unit, which may be one of a number of units for performing the method, and which includes a tank or receptacle for containing a body of liquid and having a circulating conductor connected thereto, with a pump and an injector connected therein, whereby the liquid is circulated under a relatively high velocity, the well fluid is sucked into the injector and a vacuum pulled in the well, and the well fluid is then separated from the liquid in the receptacle.

A still further object of the invention is to provide an improved unit of the character described including means for controlling and regulating the vacuum pulled on the well connected with the suction pipe from the well and a by-pass from said means to the receptacle, whereby the vacuum pulled on a particular well may be limited in accordance with the oil recovery and pumping conditions therein.

Stillanother object of the invention is to provide ,an' improved injector having a passage qtherethrough opening into a suction and atomizing chamber intermediate its ends with a Venturi section beyond the chamber and atomizing ducts whereby the velocity of a liquid forced through the passage is accelerated and a suction is 3 created in the chamber and through the inlet thereto and the liquid is atomized in the chamber, which acts to more effectively pick up the injected fluid.

A construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein an example of the invention is shown,- and wherein:

Fig. 1 is a schematic View showing a well installation made in accordance with the invention,

Fig. 2 is a side elevation of a unit constructed in accordance with the invention, partly in section to show the gas nozzle,

Fig. 3 is an enlarged, partial longitudinal sectional view of the injector,

Fig. 4 is a transverse, sectional viewof the injector taken on the line 44 of Fig. 3, and

Fig. 5 is an enlarged, vertical sectional view of the vacuum valve.

In the drawings, the numeral It designates the tank of the vacuum unit mounted on a base skid II. This unit includes a centrifugal pump H, which is also mounted on the base skid. In general the intake of the pump is connected with the lower portion of the tank by a pipe l4; while the discharge of the pump is connected with the medial portion of said tank by an upright pipe I5 and a horizontal pipe [6. An injector I1 is connected in the medial portion of the pipe [6. A water level is maintained in the tank at or below the pipe I6.

A lateral suction pipe 18 is connected in one side of the injector H and has a tee IS screwed onto its end. When the pump is in operation, water is drawn from the tank by way of the pipe 14 and discharged by the pump through the pipes l5 and it into the tank and thus a constant water circulation through the pipes is maintained. The water is discharged under a predetermined pressure and relatively high velocity and in passing through the injector head, creates a suction through the pipe 18.

The tee I9 is connected with a pipe line 29 leading to the casing head 2! on the upper end of the casing 22 of a pumping oil well. The well tubing 23, which is less in diameter than the casing so as to leave an annular space therebetween, is supported in a hanger 24 mounted on the casing head. The tubing carries the usual stumng box 25, through which the polish rod 26 reciprocates. The well elements are shown in conventional form. The suction created through the pipe is is also established in the pipe 23, casing head 2| and the annular space of the casing 22. By this arrangement a vacuum is set up at the bottom of the well.

Usually more or less gas is present in the oil at the bottom of the well and the operation of the traveling valve in the working barrel (not shown) causes churning or agitation of the oil which results in foaming due to the presence of the gas. The pumping operation also causes the gas to build up in pockets, to expand and foam gas heads. The result is that pumping wells produce more or less gas with the oil and therefore, the volume of liquid or oil, per stroke, is reduced because of the presence of such gas.

By pulling a vacuum on a well and. also upon the producing formation, as herein set forth, the free and released gas in the vicinity of the formation and the working barrel, is drawn up the anwith the method herein described, without lowering the market value of the oil per barrel.

The pump I2 is mounted on a standard 27 which supports the impeller shaft 28. A belt pulley 29 is mounted. on this shaft. Since a pumping engine or motor is frequently installed at the well, the pump l2 may be easily driven by the same. cap 30 in its top. Gas. drawn into the injector I! will be discharged with the water by the pipe l6, into the tank. 7 A gas outlet nozzle 3% is mounted in the top of the tank and connected with an exterior gas discharge pipe 32. The nozzle is of the perforated or screen type and prevents water globules being carried out with the gas.

The injector I1 is of considerable importance and while its structure may be varied, I have found the form illustrated in Figs. 3 and 4 to be most satisfactory. The injector includes a substantially horizontal cylindrical casing I3 having integral, internally screw-threaded collars 33 at its ends, which are axially alined. At'its entrance end the injector has an annular atomizing chamber 35 which is provided at one side with a lateral screw-threaded opening 35, into which the pipe 18 is screwed.

The collar 33 is co-axially alined with a nipple 31 integral with the head and extending partially across the chamber 35. An atomizing head 38 is formed in the discharge end of the nipple and drilled to form annularly spaced cylindrical ducts 39 coincident with the cylindrical wall of the bore 40 of said nipple. A tubular nozzle 4! is snugly fitted in a reduced bore 42 in the head 38 and extends across the chamber 35 into a Venturi sleeve 43; The inner end of the nozzle is upset into a flared mouth 44 in the inner end of the head 38, the inner ends of the ducts 39 opening into said mouth.

The Venturi sleeve 43 is removable and has a snug fit in an elongate bore 45 in the casing I3, being fastened in place by a set screw 4'0. The sleeve is of particular construction having a converging mouth 41, through which the nozzle extends. A cylindrical core or mixing chamber 48 extends into the sleeve from the inner reduced end of the mouth 41. From the discharge fend of the bore, the sleeve is gradually flared .outwardly to its discharge end, as indicated at 49.

The water discharged into the nipple 3?, under pressure, and velocity is directed by the mouth 44 into the ducts 39 and nozzle 4!. The water stream is thus divided into a relatively large or central stream by way of the nozzle 4|, which stream, owing to the reduced size of the nozzle is discharged into the chamber 43, under a relatively high velocity. This stream coacting with the Venturi mouth creates a draft or suetion in the head chamber 35.

While a portion of the water stream in the nipple 37 is discharged through the nozzle 4|, another portion is ejected through the ducts 39 into the chamber 35, relatively circumferentially of said nozzle. These duct streams are The tank [0 has a water filling more or less atomized by the suctionof the nozzle stream and upon entering the Venturi mouth 41 function to build up the suction in the chamber 35, acting through the opening 36 and pipe i8 to pull gas from the well casing, as well as to pick up the gas or air. A thorough mixing of the fluids takes place in the bore or chamber 43 and owing to the fiare 49 of the sleeve, the velocity of the stream is reduced as it travels to thepipe l6 and into the tank.

The pipe I6 is screwed into a transition 50 on the side of the medial portion of the tank having its bore 5| at a tangent to the inner circumferential surface of the tank. The watergas stream is thus discharged tangentially into the tank and travels a short distance on the inner surface, spreading and losing velocity. Owing to the relatively large area of the tank, the water and gas readily separate so that the water moves downwardly to the body of water in said tank and the gas rises and escapes through the nozzle 3| and pipe 32.

A tee 52 may be connected in the pipe IS in advance of the injector l1 and a pressure gage 53, mounted therein and a ed in the pipe I 8 and a vacuum gage 55 connected thereto. A check valve 56 is connected in the pipe 20, adjacent the casing head 2|, arranged to close and hold the vacuum in the well casing when the unit is shut down.

It is desirable in some installations to limit the amount of vacuum or suction pulled on the well and for this purpose a by-pass valve 51 is employed. This valve includes a cylindrical body or block 58 having screw-threads 59 at its bottom so that it may be screwed into the tee I9. The block has a vertical bore 60 therethrough for receiving a valve stem 6| of less diameter than said bore. The lower end of the stem is reduced and has a valve 62 secured thereon so as to seat against the bottom of the block which is exposed in the tee. The upper end of the stem is screw-threaded and receives nuts 63, bearing on top of a follower washer 64. A coil spring 65 is confined between the washer and the top of the block. A cap '66 enclosing the stem and spring is screwed onto the block.

A lateral port 61 leads from the bore 60 through one side of the block and this port is connected with the upper portion of the tank by a small bypass pipe 68. When ever the suction in the pipe [8 and tee 19 reaches a predetermined value,

it will overcome the expansive force of the spring 65, whereby gas will be drawn from the tank into the tee I9. By this means the vacuum on the well will be controlled. By adjusting the nuts 63 and varying the compression of the spring, the point at which the valve opens may be set.

These units have been installed on a number of wells and it has been found that satisfactory results are obtained by pulling from 12 to 20 inches of vacuum, according to the well conditions. Gas has been handled at as low as 2000 cubit feet, per day and as high as 20,000 cubit feet per day. By the use of a centrifugal pump, a constant and steady stream of water is forced through the injector and this results in a stabilized vacuum. Pump pressure varying from 25 to 40 lbs. per sq. in. have been used. The R. P. M. of the pump may vary from 800 R. P. M. to 3600 R. P. M., depending upon the amount of vacuum desired and the volume of gas an individual well is producing.

The figures and. values given are merely examples and not limitations of the invention. It

tee 54 may be connecthas'beeniound that, as ani average, a unit will dissipate about 2"gallons oi water aweek and thecapacity of the tank is such that checking and adding water every'10 days or twice a month, in hot weather and once or twice a month in colder weather, is amply sufficient.

What I claim and desire to secure by Letters Patent is:

l. A secondary well recovery unit including a tank having a body of liquid therein, a liquid circulating conductor having its ends connected to and communicating with the lower and medial portions of the tank above and below the liquid level in said tank, a pump connected in said conductor, and an injector connected in the upper portion of the conductor between the pump and the tank and having an inlet well connection.

2. A secondary well recovery unit as set forth in claim 1, wherein the tank has separating elements for, separating gas from the liquid.

3. A secondary well recovery unit including, a

tank having a body of liquid therein, a liquid circulating conductor having its ends connected to and communicating with the lower and medial portions of the tank above and below the liquid level in said tank, a pump connected in said conductor, an injector connected in the upper portion of the conductor between the pump and the tank and having a suction inlet, a pipe connected with the injector inlet, a vacuum control valve connected with the pipe, and a by-pass conductor extending from the valve to the tank above the liquid level therein.

4. A secondary well recovery unit including,

an upright cylindrical tank having a body of liquid therein, a gas outlet at the top of the tank spaced above the liquid level in said tank, an inlet fixture on the side of the tank having a discharge conductor communicating with the tank above the liquid level therein, a circulating conductor having one end connected to the fixture and its other end connected to the lower portion of the tank for receiving liquid therefrom, a pump connected in the conductor, and an injector connected in the conductor between the pump and the fixture and having a lateral fluid inlet.

5. A secondary well recovery unit as set forth in claim 4, with a fluid inlet pipe connected to the inlet of the injector, a vacuum control valve connected to said pipe, and a by-pass line from the valve to the tank above the liquid level therein.

6. A system of secondary recovery in oil wells which includes, a pumping well which is cased and closed at its upper end by a casing head and having an oil production tubing packed oif therein and extending down into the well, said casing head and casing being air tight to permit the pulling of a vacuum in said casing and through said head, a tank containing a body of liquid up to a level below its upper end, a tubular liquid circulating conductor connected to and communicating with the tank at upper and lower levels one of which is above and another of which is the liquid level and having a liquid circulator connected therein, an injector connected in the conductor for creating a liquid circulation from the lower portion of said tank to the upper portion thereof above the liquid level therein and a suction through said injector, and a tubular conductor for connecting the injector with the well casing outside the production tubing i for creating a vacuum in the well acting upon the producing formation thereof.

7. A. system as set forth in claim 6, wherein aspace is provided in the tank above the liquid level for separating gas from the liquid.

J EDDY D. NIXON.

REFERENCES CITED Number -UNITED STATES PATENTS Name Date Elliot May 2, 1865 mncaid Dec. 8, 1931 Fink June 11, 1935 Dunham July 30, 1935 Wolf Apr. 26, 1938 Bays Apr. 25, 1939 Pyle Nov. 21, 1939 Bergh -1 May 27, 1947 

